We are feeding semipurified, cholesterol free diets to Vervet monkeys. These diets have been shown to cause hyperlipemia and aortic sudanophilia in this species. The diets will contain special fats which differ in their levels of oleic and elaidic acid. In addition to effects on serum and liver lipid levels, we are investigating the effect of these diets on serum and tissue fatty acid spectra and on activity of membrane-bound enzymes such as glucose-6-phosphatase and malate dehydrogenase. An experiment comparing the atherogenic effects of native and randomized peanut oil is also in progress. We are comparing the interactions of casein and soy protein with cellulose and pectin using a semipurified diet.